I did nearly this exact same thing circa Fall 1979. Lucky for me, the big wheel came out from under me, I let go of the handlebars and to the amazement of myself and all my friends, I ended up landing on my feet and running the momentum out. I felt like a super hero and my friends were whooping and hollering as kids do. Then I tried it again. And that's the story of how I got the scars on my knees and how my new Star Trek pants became my new Star Trek shorts. Ah, the folly of youth.